The present invention generally relates to expandable sheet articles, and in particular to a foam sheet that is expandable.
Expandable foam sheet is made by providing solid foam sheet with a plurality of slits so that mechanical force can be applied to the foam sheet to expand it in one or more directions. Expansion in one direction can form a honeycomb-type structure. Expandable foam sheet has been designed to be expanded along its length, or along its width, or even in both length and width. Expandable foam sheet has been taught for a variety of uses, such as in flooring systems, as carpet underlayment, thermal insulation sheet for garments, pipes and conduits, self-inflating mattresses, concrete blanket, and concrete underlayment.
Expandable foam sheet made from thermoplastic foam such as polyethylene foam exhibits elastic character during expansion. That is, as force is applied to expand the foam sheet in one or more dimensions, the foam sheet exhibits an elastic restorative force that, unless opposed, results in the foam sheet returning to its unexpanded configuration. Typically, means external to the foam itself, such as adherence of the expanded foam sheet to a rigid member with an adhesive, retains the foam sheet in its expanded configuration.